1. Technical Field
The present invention relates to a stacked-layered thin film solar cell and a manufacturing method thereof. More particularly, the present invention relates to a manufacturing method which forms an interlayer and creates an isolation effect for a stacked-layered thin film solar cell by using a mask.
2. Description of Related Art
Generally speaking, a conventional stacked-layered thin film solar cell comprises a substrate, a first electrode layer, a light-absorbing layer and a second electrode layer in a series stacked structure. In a following packaging process, for eliminating problems about short-circuit faults and electric leakage, U.S. Pat. No. 6,300,556 proposes a method involving forming an isolation groove by scribing the solar cell near a periphery thereof for partially removing the first electrode layer, the semi-conductor layer and the second electrode layer, and the mechanically removing the first electrode layer, the semi-conductor layer and the second electrode layer or films of the three layers outside the isolation groove near a periphery of the substrate. In addition, the disclosure of U.S. Pat. No. 6,271,053 involves depositing the layers, dividing the deposited layers into serially connected solar cells, removing the second electrode layer and semi-conductor layer at peripheries of the cells so as to reveal the semi-conductor layer, and then thermally processing the revealed semi-conductor layer to oxidize its surface and thereby increase its resistance. Since the isolation grooves are formed by two types of laser beams of different wavelengths, the manufacturing procedures are complicated and therefore equipment costs as well as manufacturing cycle are enlarged. Furthermore, after the cutting process is performed, due to possible unevenness of the laser beams, part of the second electrode layer may be not fully removed and, in its melt state, remains on the first electrode layer, leading to short-circuit faults. Though using a single type of laser in length to process the three layers facilitates simplifying the manufacturing procedures, it is notable that the resultant thermal effect is greater and thus the induced short-circuit problem is more significant. Moreover, when thermal treatment is implemented at the late stage of the manufacturing procedures to oxidize the semi-conductor layer and thereby increase its resistance for averting the short-circuit problem, equipment costs and manufacturing cycle can be accordingly increased. Moreover, an interlayer is usually arranged between a material of a higher energy level and another material of a lower energy level so that when light passes through the stacked-layered thin film solar cell, a portion of the light having short wavelengths that can be absorbed by the material of the higher energy level is reflected to extend a light path while a portion of the light having long wavelengths that can not be absorbed by the material of the higher energy level is led to the material of the lower energy level so as to improve light transmission. For example, U.S. Pat. No. 5,021,100 proposes a dielectric selective reflection film in a stacked-layered thin film solar cell. Since the interlayer, for connecting materials of different energy levels, possesses electric conductivity, electric leakage and short-circuit faults can easily happen during an edge isolating process of the interlayer. Therefore, U.S. Pat. No. 6,632,993 further provides cutting grooves scribed on the interlayer for eliminating electric leakage when a current passes through the interlayer U.S. Pat. No. 6,870,088 also suggests a similar approach but further provides scribed grooves on a photoelectric conversion layer between cutting grooves so as to eliminate the above-mentioned problems. However, all of theses conventional approaches fail to address solutions to short-circuit faults at the edge of the battery. Therefore, a favorable solution to eliminate the above-mentioned problems is urgently in need.